This research represents a continuation of our studies on alpha-D-galactosyl-containing glycoproteins present on certain animal cells and tissues. We will focus attention on the carbohydrate moieties of two basement membrane and cell surface glycoproteins: laminin and entactin, both of which contain alpha-D-galactosyl end groups. Laminin is believed to be present on the surface of highly metastatic cells. Structural and biosynthetic studies will be conducted on the carbohydrate residues of these glycoproteins as well as on the alpha-D-galactosyl-terminated glycoproteins present on the surface of Ehrlich tumor cells. Purified lectins of known carbohydrate binding specificity, antibodies raised against murine laminin and against a trisaccharide hapten present as part of the structure of these glycoproteins, will be employed in these studies. An attempt will be made to protect mice against a lethal dose of Ehrlich cells by immunizing the mice with the trisaccharide-protein conjugate. The appearance of cell surface laminin, which is expressed on stimulated but not resident murine macrophages, will be quantified under various conditions of stimulation using a lectin-enzyme conjugate. Biosynthetic studies will include an investigation of the incorporation of D-galactose and N-acetyl-D-glucosamine into the polylactosamineglycan that forms part of the structure of these alpha-D-galactosyl-terminated glycoproteins. We shall characterize an alpha-D-galactosidase present in Ehrlich ascites tumor cells and that probably is involved in the biodegradation of alpha-D-galactosyl-containing glycoproteins. The localization of alpha-D-galactosyl-terminated glycoconjugates in a variety of cells by electron microscopy will be conducted using a colloidal gold complex of Griffonia simplicifolia I-B4 isolectin, a probe specific for alpha-D-galactosyl end groups. We shall also attempt to select and characterize a variant of Ehrlich ascites tumor cells that lack alpha-D-galactosyl groups. (A)